1. Field of the Invention
The invention relates to an apparatus for separating threshed leaf tobacco with minimum degradation and in particular avoiding the use of rotary airlocks and rotary infeed projecting devices.
2. Description of Background Art
Tobacco in the form of threshed leaves comprises lamina, lamina with attached stem, stem and stem with attached lamina. It is necessary to separate the lighter tobacco particles from this mixture. Normally, conveyors and fans are used to assist in this separation operation.
Hithertofore, apparatus for separating lighter particles from tobacco particles contained in threshed leaf tobacco included separator units each including a separation chamber having a fan system for establishing a generally upward air flow within the separation chamber. A tobacco particle projector is required to project tobacco particles across the air flow in the chamber so that lighter particles are carried upwardly by the air flow within the chamber. An endless foraminous conveyor is provided within the separation chamber that extends upwardly from the projecting side of the chamber to the receiving side thereof
Currently available separating apparatus requiring a particle projector, or inlet winnower, and an inclined foraminous conveyor have some deficiencies. More specifically, the heavier tobacco particles have a tendency to gravitate to the lowest point in the separation chamber. In view of the fact that the lowest point corresponds to the area adjacent to the location of the particle projecting mechanism, efficient operation of the separator apparatus does not occur.
Buildup of tobacco particles in an area adjacent to the location of the particle projecting mechanism not only tends to form a blockage but also tends to damage the threshed leaf tobacco. In addition, there is a tendency that heavier particles discharging from the apparatus contain lighter particles clumped together. Thus, it is required to provide an additional handling unit to facilitate the separation of these particles.
According to the present invention, threshed tobacco leaves are separated by using a covered, high speed conveyor that is inclined to deliver tobacco particles into a separator chamber. The covered, high speed conveyor is angled to achieve the correct trajectory of product into the chamber to ensure separation of the lighter tobacco product from the heavier tobacco product.
An upward air stream within the chamber separates the lighter material and conveys it pneumatically to a separating unit to enable the product to be discharged from the air stream. The air is recirculated back to the chamber and enters the chamber through a lower plenum chamber.
Heavier particles of tobacco fall onto an integral perforated conveyor that carries the product to the next covered, high speed conveyor for feeding the next separating chamber. The perforated conveyor is disposed to be substantially horizontal or declined as the conveyor extends across the separating chamber.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modification within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.